Dec. 20, 1915 Cherry and Hawthorn Sawfly Leaf Miner 527 



Profenusa coUaris has been under observation, T. minutum has twice 

 made its appearance in conspicuous numbers in infested cherry orchards, 

 in 1 91 2 and in 191 5. During the former year the larger percentage of the 

 eggs of the leaf miner were attacked, and on some trees it was difficult to 

 find an egg-bearing leaf which had not been visited by the parasite. In 

 1 91 5 parasitism ranged from about 40 to 90 per cent on individual trees. 

 Taking all trees into consideration, of the eggs deposited by the insect a 

 larger percentage of them certainly failed to hatch than hatched, and for 

 this mortality T. viinutum appeared to be largely responsible. 



The parasite was reared from both cherry and hawthorn foliage. The 

 majority of the eggs of the leaf miner that were dissected contained a 

 single parasite, and in only a few instances were twin larvae or pupae 

 observed. On June 2, 1915, the parasites were all in the larval state, 

 but on June 5, when the larvae of P. collaris were beginning to abandon 

 their mines in the foliage, about 50 per cent of the parasites were in the 

 pupal state. By June 7 they had nearly all transformed to pupae, and 

 on June 9 the first adult appeared. During succeeding days the chal- 

 cidids appeared in large numbers, and the last specimen to make its 

 appearance emerged 'on June 14. While the parasite was abundant about 

 Geneva during this year, it was relatively quite scarce on plantings of 

 Crataegus spp. at Rochester. 



Besides the foregoing parasite there has been reared from P. collaris 

 an ichneumon which proved to be a new species and has been listed by 

 Rohwer ^ as " Pezoporus tenthredinarum." Apparently there is associated 

 with this ichneumon an undescribed tryphonine, but owing to the small 

 numbers collected it is impossible to make any definite statement at this 

 time as to its status as a parasite of the sawfly leaf miner. 



METHODS OF CONTROL 



REMOVAL OF AFFECTED LEAVES 



Of the operations systematically practiced, one that will probably 

 prove most effective and economical in controlling the sawfly leaf miner 

 is the picking of affected leaves. This species is peculiarly susceptible 

 to this kind of repressive method, since there is only one brood of larvae 

 to attack the foliage, and oviposition extends over only a short period. 

 The effect is that hatching of eggs and maturing of larvas are, practically 

 speaking, almost simultaneous for all of the creatures, and their activities 

 during their injurious stages are therefore restricted to a relatively short 

 period. By careful timing it is possible at a single picking to collect 

 practically all of the larvae by removing the affected leaves, which should 

 then be burned to destroy the insects therein. The removal and de- 

 struction of all mined leaves, coupled with another practice — the destruc- 



• Rohwer, S. A. Descriptions of new species of Hymenoptera. In Proc. U. S. Nat. Mus., v. 49, p. 216. 

 1915. 



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